This invention relates to boxes or cartons of the type used to carry heavy loads and, more particularly, to boxes of that type which are intended to be stacked one on top of the other. For example, boxes of this type may be used to pack and ship fish and it is not uncommon for a single box to contain between 100 to 150 pounds of fish. Typically, after a box is filled and its cover in place, another similarly loaded and covered box will be stacked on the first box, as will be subsequently filled boxes. As a result, the lower boxes in the stack may be under a very substantial load. In order to be able to support the load, such boxes typically are formed from very heavy material and often are provided with covers having full length skirts which extending downwardly to the bottom wall of the box. The full length skirt provides a measure of additional lateral structural support for the box and, at least as far as the bottom box in the stack is concerned, the lower edge of the skirt may rest directly on the floor and also provide some additional measure of support to the vertically directed weight of the upper boxes in the stack.
It is among the general objects of the present invention to provide an improved box structure in which each box has a projection at each of its four corners which is disposed to support the lower edge of the corner portions of the skirt of the cover. This avoids the necessity for using full length skirts and also enables the load of successively stacked boxes to be transferred to the corner regions of the lower boxes which are the strongest regions of the boxes and are best able to resist the loads. In addition to providing a means to direct a substantial part of the load to the corner regions of the boxes, the invention also enables covers having relatively short skirts to be used which results in a less expensive box structure.